The invention specifically applies to the independent brake line of a locomotive. More specifically, it applies to the 20 line in the EPIC.RTM. 3102 braking system. In general, it applies to removal of liquid contaminants from a gas conduit which is normally at zero pressure or at a steady positive pressure and which at times is subject to pressure variations.
The independent brake system of a locomotive operates independently of the main airbrake system that includes the brake air line which is connected between all the railway vehicles in a consist of coupled railway vehicles. The independent brake system applies brakes only in the locomotive. It is used, for example, when a locomotive is not connected to other railway cars, but is moved independently within a switchyard or a maintenance facility.
The independent brake system of a locomotive has a brake air line which is pressurized to apply brakes in the locomotive and is depressurized to release brakes. The independent brake system works in a manner exactly opposite to the main airbrake system of a train, in which the brake line is pressurized to release brakes and depressurized to apply brakes.
In addition to its use for controlling an isolated locomotive in a switchyard or maintenance facility, the independent brake system is also used on other occasions when it is desired to apply brakes in the locomotive but not in the other railway cars. For example, it is generally desirable for an engineer to place all the cars in a train in either a tension mode, or in a compression mode to reduce impact forces on couplers and draft gears due to relative motion of coupled cars. To place a train in a compression mode, as for example, prior to descending a grade, an engineer may retard the locomotive using the independent brake system so that the line of cars compresses against the locomotive.
The EPIC.RTM. 3102 Braking system uses transducers to measure the pressure in the 20 line. Difficulty has been experienced during winter weather conditions due to freezing of moisture in the 20 line. The transducers which measure pressure in the 20 line may freeze, or the fluid pathways to the transducers may become blocked with ice. Accordingly, it is necessary to remove condensed moisture from the 20 line. The 20 line may also have other fluid contaminants such as oil droplets and it is desirable to purge these from the system.